Because the book attempts to represent evil well, there is a good amount of content that may disturb younger or more sensitive readers. It is not 'graphic' in the way that many books are, but there are multiple perilous and potentially frightening scenes and creatures. There is a dragon and other other-worldly creatures, some of which chase the main character. In a more our-worldly scene, Owen is chased and eventually jumped by a bully. Later he imagines what could happen in a robbery. Knowing your child will be key here as this is certainly rewarding for those who can handle all of this.
